Heat oil in a large nonstick skillet over medium-high heat. Add the fish, working in batches if necessary, and cook until lightly browned and just opaque in the center, 3 to 4 minutes per side. Serve each portion of fish with about 1 tablespoon sauce each.

Make Ahead Tip: Cover and refrigerate the sauce (Step 1) for up to 3 days.

Tilapia: U.S. farmed tilapia is the considered the best choiceit's raised in closed-farming systems that protect the surrounding environment. Central and South American tilapia is considered a good alternative. Avoid farmed tilapia from China and Taiwanwhere the fish farming pollutes the surrounding environment.

Haddock (Scrod): To get the best choice for the environment, ask for U.S. Atlantic “hook-and-line-caught” haddockthis method causes the least damage to the sea floor and has the least by catch.